Local Area Networks (LAN) are an integral part of today's homes and businesses, linking computers, printers, and servers. When one of these devices is connected to a LAN, it is assigned a unique network address to be used for as long as the connection is maintained. Increasingly, these networks have also included wireless connectivity. With the popularity of wireless networks increasing, there is a push to provide more services over wireless connections. Besides the traditional data communication support, WLANs are expected to support voice and video applications.
Client devices that support wireless communication typically are equipped with a wireless communication card or an embedded wireless communication module that allows for receiving and transmitting data to and from a wireless AP. The AP is usually attached to the wired LAN and can incorporate a router as a gateway to the wide area network (WAN) for Internet access. A LAN is not restricted to one AP, and in many circumstances, multiple APs are dispersed throughout a facility like an office building or home to provide extended wireless coverage.
The wireless client and AP go through an authentication and association process before the wireless client can establish communication with the LAN, router or WAN. This process is defined in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, incorporated herein by reference. The AP and wireless device connect through one of a plurality of service set identifiers (SSID) available to the AP for establishing a communications pathway. Generally, the wireless device has a default SSID which may be user defined and the AP has a plurality of SSIDs which the wireless device can use to establish a communications pathway. During this process, the wireless client is assigned a network address by the AP.
Commercially available APs generally have a communication range of less than 100 m. However, this range is affected by a number of factors such as, e.g., the location of the AP, indoor vs. outdoor, obstructions, antenna location and type, and output power. When these factors are taken into account, the AP's range is generally limited to a relatively small area such as several rooms in a house or building. To increase the coverage area, more APs wired to the LAN can be added to locations where wireless access is not available. Within the coverage area of an individual AP, a wireless client device can enjoy the benefits of the network, including services provided by the WAN. However, there are limits to the services that wireless clients enjoy.
Most services used by a wireless client require a unique network address associated with the client. This network address is generated when the client first establishes communications with the AP. A challenge occurs when there are multiple APs on a LAN and the wireless client device roams between two or more APs. When a wireless client device is authenticated and associated with an AP, it is assigned a network address that in part indicates which AP the wireless device is using as part of its communication pathway. This address is only valid for wireless communications through that particular AP. The wireless client device generally uses a different address when communicating through a different AP. Therefore, if the wireless client was to roam to a new AP, the previously assigned network address is no longer valid.
The IEEE has recognized this as an impediment to wireless networks. In an effort to address this problem, it developed protocol 802.11R (fast roaming). Intended to refine the transition process of a mobile client as it moves between APs, this protocol permits client devices to retain their networking address as they moves between APs. However, this does not fully address the challenge.
Using 802.11R, a wireless client device can roam to a new AP and still transmit data to the correct destination on the WAN or LAN. However, data transmitted to the wireless device will be routed to the previous AP which the wireless client is no longer associated with. This means that the wireless client device will not receive data intended for it.
Therefore, what is desired is a method for providing the retention of a wireless client communication pathway for transmitting and receiving data as the client roams from between two or more APs wired to the same LAN.